Bài 3 Tìm x : a,180-2.(x-15)=$2^{3}$ . 5 b,[(6x-39):7].4=12 c,10x-$2^{3}$ .5=$10^{3}$ :$10^{2}$ GIẢI CHI TIẾT RA HỘ MIK NHA

$\text{a) 180 – 2.(x – 15) = $2^3$.5.}$

$\text{⇒ 180 – 2.(x – 15) = 8.5.}$

$\text{⇒ 180 – 2.(x – 15) = 40.}$

$\text{⇒ 2.(x – 15) = 180 – 40.}$

$\text{⇒ 2.(x – 15) = 140.}$

$\text{⇒ x – 15 = 140 ÷ 2.}$

$\text{⇒ x – 15 = 70.}$

$\text{⇒ x = 70 + 15.}$

$\text{⇒ x = 85.}$

$\text{Vậy x = 85.}$

$\text{b) [(6x – 39) ÷ 7].4 = 12.}$

$\text{⇒ (6x – 39) ÷ 7 = 12 ÷ 4.}$

$\text{⇒ (6x – 39) ÷ 7 = 3.}$

$\text{⇒ 6x – 39 = 3.7.}$

$\text{⇒ 6x – 39 = 21.}$

$\text{⇒ 6x = 21 + 39.}$

$\text{⇒ 6x = 60.}$

$\text{⇒ x = 60 ÷ 6.}$

$\text{Vậy x = 10.}$

$\text{c)10x – $2^3$.5 = $10^3$ ÷ $10^2$.}$

$\text{⇒ 10x – 8.5 = 10.}$

$\text{⇒ 10x – 40 = 10.}$

$\text{⇒ 10x = 10 + 40.}$

$\text{⇒ 10x = 50.}$

$\text{⇒ x = 50 ÷ 10.}$

$\text{Vậy x = 5.}$